content: /*
   * This file is part of Sponge, licensed under the MIT License (MIT).
   *
   * Copyright (c) SpongePowered <https://www.spongepowered.org>
   * Copyright (c) contributors
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to deal
   * in the Software without restriction, including without limitation the rights
   * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   * copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
   * THE SOFTWARE.
   */
  package io.akarin.server.mixin.optimization;
  
  import java.util.UUID;
  
  import javax.annotation.Nullable;
  
  import org.spongepowered.asm.mixin.Final;
  import org.spongepowered.asm.mixin.Mixin;
  import org.spongepowered.asm.mixin.Overwrite;
  import org.spongepowered.asm.mixin.Shadow;
  
  import com.google.common.base.Optional;
  
  import net.minecraft.server.DataWatcherObject;
  import net.minecraft.server.Entity;
  import net.minecraft.server.EntityTameableAnimal;
  import net.minecraft.server.World;
  
  @Mixin(value = EntityTameableAnimal.class, remap = false)
  public abstract class MixinEntityTameableAnimal extends Entity {
      @Shadow @Final protected static DataWatcherObject<Optional<UUID>> by;
      
      @Nullable private Optional<UUID> cachedOwnerId;
      
      @Nullable
      @Overwrite
      public UUID getOwnerUUID() {
          if (cachedOwnerId == null) cachedOwnerId = datawatcher.get(by);
          return cachedOwnerId.orNull();
      }
      
      @Overwrite
      public void setOwnerUUID(@Nullable UUID uuid) {
          cachedOwnerId = Optional.fromNullable(uuid);
          datawatcher.set(by, cachedOwnerId);
      }
      
      /**
       * Extends from superclass
       * @param world
       */
      public MixinEntityTameableAnimal(World world) {
          super(world);
      }
  }
  